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Re: [Qemu-devel] Re: [PATCH] pc: e820 qemu_cfg tables need to be packed
From: |
Arnd Bergmann |
Subject: |
Re: [Qemu-devel] Re: [PATCH] pc: e820 qemu_cfg tables need to be packed |
Date: |
Thu, 14 Oct 2010 22:20:25 +0200 |
User-agent: |
KMail/1.13.5 (Linux/2.6.31-19-generic; KDE/4.5.1; x86_64; ; ) |
On Thursday 14 October 2010 21:58:08 Alex Williamson wrote:
> If it works anywhere (I assume it works on 32bit), then it's only
> because it happened to get the alignment right. This just makes 64bit
> hosts get it right too. I don't see any compatibility issues,
> non-packed + 64bit = broken. Thanks,
I would actually assume that only x86-32 hosts got it right, because
all 32 bit hosts I've seen other than x86 also define 8 byte alignment
for uint64_t.
You might however consider making it
__attribute((__packed__, __aligned__(4)))
instead of just packed, because otherwise you make the alignment one byte,
which is not only different from what it used to be on x86-32 but also
will cause inefficient compiler outpout on platforms that don't have unaligned
word accesses in hardware.
Arnd
- [Qemu-devel] [PATCH] pc: e820 qemu_cfg tables need to be packed, Alex Williamson, 2010/10/14
- [Qemu-devel] Re: [PATCH] pc: e820 qemu_cfg tables need to be packed, Jes Sorensen, 2010/10/14
- Re: [Qemu-devel] Re: [PATCH] pc: e820 qemu_cfg tables need to be packed, Anthony Liguori, 2010/10/14
- Re: [Qemu-devel] Re: [PATCH] pc: e820 qemu_cfg tables need to be packed, Alex Williamson, 2010/10/14
- Re: [Qemu-devel] Re: [PATCH] pc: e820 qemu_cfg tables need to be packed, Anthony Liguori, 2010/10/14
- Re: [Qemu-devel] Re: [PATCH] pc: e820 qemu_cfg tables need to be packed,
Arnd Bergmann <=
- Re: [Qemu-devel] Re: [PATCH] pc: e820 qemu_cfg tables need to be packed, Alex Williamson, 2010/10/14
- Re: [Qemu-devel] Re: [PATCH] pc: e820 qemu_cfg tables need to be packed, Arnd Bergmann, 2010/10/14
- Re: [Qemu-devel] Re: [PATCH] pc: e820 qemu_cfg tables need to be packed, Alex Williamson, 2010/10/15
[Qemu-devel] [PATCH v2] pc: e820 qemu_cfg tables need to be packed, Alex Williamson, 2010/10/15